How do we cache http response with koa?

by muriel.schmidt , in category: Javascript , 2 months ago

How do we cache http response with koa?

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1 answer

by arnoldo.moen , 2 months ago

@muriel.schmidt 

In Koa, you can cache HTTP responses using various middleware and techniques. Here are a few approaches you can take:

  1. Koa-etag: The koa-etag middleware calculates and generates an ETag for an incoming response and adds it as the ETag header. It also handles the If-None-Match header for cache validation. You can install it using npm:
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npm install koa-etag


To use it in your Koa application:

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const Koa = require('koa');
const etag = require('koa-etag');

const app = new Koa();

app.use(etag());

// Your routes and middleware

app.listen(3000);


  1. Koa-static-cache: This middleware caches static files (e.g., CSS, JavaScript, images) by adding the Cache-Control and Last-Modified headers. It allows the client to send a conditional GET request with the If-Modified-Since header. You can install it using npm:
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npm install koa-static-cache


To use it in your Koa application:

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const Koa = require('koa');
const staticCache = require('koa-static-cache');

const app = new Koa();

app.use(staticCache(path.join(__dirname, 'public'), {
  maxAge: 365 * 24 * 60 * 60, // Cache for 1 year
}));

// Your routes and middleware

app.listen(3000);


  1. Custom caching: You can implement your own caching logic using Koa's middleware. Here's an example of caching a response for a specific duration:
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const Koa = require('koa');

const app = new Koa();

// Cache middleware
app.use(async (ctx, next) => {
  // Generate a unique cache key
  const cacheKey = ctx.url;

  // Check if cache key exists
  const cachedResponse = cache.get(cacheKey);
  if (cachedResponse) {
    // Serve the cached response
    ctx.body = cachedResponse;
    return;
  }

  // Execute downstream middleware
  await next();

  // Cache the response for 5 minutes
  cache.set(cacheKey, ctx.body, 5 * 60 * 1000);
});

// Your routes and middleware

app.listen(3000);


In the above example, the cache object represents a cache store (e.g., Redis, Memcached) that you can use to store and retrieve cached responses. Make sure you have a cache store installed and configured.


Remember to adjust the caching mechanism based on your application's needs and cache invalidation strategies.